Attention, Jack Nicholson obsessives: The owner of the West Coast wildman’s childhood home in Neptune, N.J., is putting the six-bedroom Cape Cod house on the auction block. Opening bids on eBay start at $449,000.

Nicholson was born in the Jersey Shore community on April 22, 1937, and attended nearby Manasquan HS where he focused on drama and was the vice president of the class of 1954. To classmates, he was Jackie or Nick, and was voted “Class Clown.”

Among his associates was actor Danny DeVito, who was also raised in Neptune, although he is seven years Nicholson’s junior.

According to local legend, Nicholson would sit on the house’s front steps – less than a mile from the beach – waiting for the first neighbor going to the local movie theater to give him a ride so he could see the matinee.

Four years after graduating, Nicholson picked up his first acting credit as Jimmy Wallace in “The Cry Baby Killer.”

Forty-six years later, he paid a surprise visit when the class had its 50th reunion, classmates said.

“He didn’t let us know he was coming,” said Sally Krum.

Years earlier, they all predicted he would have two Academy Awards by the time of the 50th reunion, she said.

“He said ‘I just want to point out you all underestimated me,'” she recalled – Nicholson picked up his third in 1998 for “As Good as It Gets.”

He previously took home Oscars for “Terms of Endearment” and “One Flew Over the Cuckoo’s Nest,” and has been nominated for an astonishing nine more.

Since then, Nicholson has been associated with all things left coast – a staple at Lakers games and an impressive laundry list of bedded Hollywood starlets on his résumé.

His home is on a stretch of Mulholland Drive in Beverly Hills dubbed “Bad Boy Drive” because of neighbors who included heartthrobs Warren Beatty and the late Marlon Brando.

Despite the Hollywood exploits, the Jersey Shore house factors in one of the stranger aspects of the A-list actor’s wild life.

His staunchly Catholic grandparents, Ethel May and John Nicholson, raised him there – but told him they were his parents.

His actual mother – a vaudeville singer who gave birth to him when she was 17 after a scandalous affair with a married man – pretended to be his sister.

He would only later learn the truth when a Time magazine reporter doing a profile in 1972 on the young and upcoming star who had just wrapped up work on “The Last Detail” discovered the truth.

His mother, June, died of cancer in 1963. Nicholson has gone on to sire five children – three girls and two boys.

The house’s current owner, real estate broker Sabrina Digiuseppe, has a copy of the star’s birth certificate bearing the home’s address – 1410 Sixth Ave. – to reassure prospective buyers that the house was actually Nicholson’s.

“His birth certificate has my address on it,” she told The Post. “They lived here from the time he was a baby till the time he was about 9. I’ve had people on my front porch taking pictures for years.”

His agent, Sandy Bressler, said the actor could not be reached to confirm if it was his house, but had no reason to dispute it.

“He did live in Neptune,” he said.

With housing sales declining nationwide will the house’s pedigree help it sell?

“I don’t think its going to become a historical landmark or anything,” Bressler said. “But I guess people who are willing to buy a cookie shaped like Jesus’ head on eBay will be willing to buy anything.”